Coffee-roasting machine



May 27,l 1930. J. F. QUINN 1,759,955

COFFEE RoEsTING MACHINE Filed Jan. 16, 1929 5a l 7 l INI/EN TOR.

JosEPl-l Ff QUINN. B f

' M v y ATTORNEYS.

I Patented .May 27,v l90 "UNITED" STATES PATENT OFF lcs JOSEPH 5F.Quinn,l OF BURLINGAME, CALIFORNIA, AssIGNOa To GEO. W. cAswELI. co.,4 lOI' SAIT FRANCISCO, CALIFORNIA, A CORPORATION or' OALIFORNIA`COIEIF'IIEIEEI-IIRDAS'JJING MACHINE Application led January 16, 1929.Serial No. 332,829.

1o Before taking up a description of the invention it would be well tostate that coffee' is generally roasted in revolving cylindrical drums,and usually there are-two cylinders one within the other, with the coieeto be 'roasted' placed in the space betweenthe cylinders. The cylindersare perforated with ne holes and gas burners are positioned within theinner cylinder to produce the necessary roasting heat. These gas burnersgenerate products of combustion which are vented through theperforations of the cylinders for discharge to .an outerhousin'g inwhich'the cylinders revolve, and from the housin they pass to the stack.The prod- $6 ucts o combustion therefore come at all times in directcontact with the coffee beans,

in fact pass through the mass of revolving coifeecontinually during theroasting process and therefore communicate objectionable matter to thecoffee for absorption thereby, thus tending to contaminatevthe sameandimpart objectionable flavor to the rresulting product. v

Besides the above objection is the diiculty of maintaining an even heatdue to the varying quality or pressures of thegas, and-the humidity andtemperature of the air of combustion supplying the flame. In fact theconditions vary so much that absolute timing of the roastingperiod undersuch conditions is very unusual in coffee roasting practice, but

where best results are the aim, reliance is placed on the expertattendant roaster who plete. When the roasting is adjudged complete, thegas llame is extinguished and a quantity of cold water is injected intothe mass of revolving coffee beans in the roaster, so. as to I0 quicklycheck the roasting process. This judges by color only when the roastin'gis com'- l water turns at once into steam sincethe temi -perature of theroasted beans is about 350 Fahrenheit, and this brings in anothervariable adapted to influence flavor and uniformity of quality.

I have discovered that the uncertainties of roasting with gas and theobjectionable contamination of the coffee resulting therefrom may beovercome by the apparatus and.

method of the invention to be disclosed.

Briefly describedmy invention comprises continuously passing a thin flatlayer of coffee beans along a surface while tumbling them over and over,and maintaining a plane of radiant heat just above and close to thebeans during their travel, so that all parts of eachbean are exposed tothe same degree of heat, and all for a. time period so that upondischarge from the plane of radiant heat the roasting will be complete,and since the travelin layer of beansA is substantially' one layer thicthel roasting effect is instantaneously checked at the end of thetreatment withoutthe necessity vof introducing water as inthe gasprocess.

Also, the plane of radiant heat is preferably derived from an overlyingnetwork or mulwith heat radiating and reflecting surfaces tiplicity ofelectrical heating units associated of beans there are no moist vaporspassing vthrough the beans` to. have any cooking tendency upon them asdo the hot moist vapors of the gas liame used in the mannerdescrl ed, Orthe natural moist vapors generated in a lolly or mass of the` beansbeing roasted in The result of the process described gives a coee ofexceptionally. hi h quality, every bean of which is individua y roastedby-being turned over'and over for exposure to the downwardly directedrays of radiant heat,

entirely free from contamination of any foreign agencles whatsoever, orAthe carryn away in a violent u rush of moist vaporso its valuablevolati'hzed constituentss and aV product which may be continuo yproduced of uniformly. unvarying quallty without expert attention.

-bring it within th v"Fig.'2 is an a relatively long box or housing 1,generallyfrom 10 to 25 or more feet in length, and which may be made ofeither wood or metal, and if of sheet metal it is preferably entirelyinsulated with heat insulating material such as asbestos or the like asindicated at 2.

' Thisbox or casing 1 may be horizontally disposed, but preferably it isgiven a slight downward inclination as shown in Fig. 1 and isconveniently supported on suitable frame members as indicated at 3.

. part o mesh so as to pass Both endsof the box are closed except for asmall opening atthe upper end fitted with -a delivery chute 4 and asimilar opening at the lower end for the discharge of material from asmall chute 5, and for the chaff adjacent chute 5. p

The interior lof the box, at least the upper portion and the two sides,are also preferably eat insulated with asbestos material as shown at 6,and about midway between the top and bottomof the box and extending for.the full length thereof is a wire screen plate 7 arranged for operationas a shaker table for slowly moving a layer from the upper to the lowerend of the box.

This shaker plate7 is of a relatively rough weave so as to turn thebeans over and over during the shaking of thedevice, and is of a thechai released from the beans both by the shaking action and by theexpansion dueto the heating of the beans. The screen plate 7 isreinforced around its edges with a suitable frame and along the sidesthe frame is extended upwardly as indicated at 8 to prevent the layer ofbeans from workin out over the edges during their travel along t escreen. Secured to the frame 8 and assing transversely across the lowerthe screenat intervals along the box are supporting bars 9 which extendthrough apertures in the boxI of a size to permit the required shakingmovement to the screen, and the free endsI of these b ars 9 4outside ofthe box are supported on vertically extending sprin metal strips 10secured at their upper ends y riveting the bars 9 and at their lowerends to a portion of the framework'as best indicated in Fig. 3 at 11.The spring metal strips 10 are arranged with their flat sides in amanner to permit vibration of the screen plate 7 longltudinally withinthe box 1. The screen is of coffee beans '28 is a continuous or otherheat lnsulating and reflecting mateor welding, or otherwise to flexiblestrips of spring metal rigidly secured lto one of the bars 9 at one endand atV the other end each provided with a split bearing 15 whichpositions around a slight eccentric portion of the shaft 13 so'as togive an osci ating movement of about an eighth ofy an inch when shaft13-is revolved. Shaft-13 is revolved by means of suitable reductionbelting as indicated at 16 and 17 passing over pulleys on a countershaft18, and run from an electric motor 19 or any other prime mover desired.speed of revolution of about 75() turns per minute on shaft 13 has beenfound satisfactory in practice with the throw of labout one eighth of aninch' of the eccentric portion of the shaft. v

'At opposite ends of the box 1 and adjacent the bottom thereof arepulleys or sprockets 20, 21 mounted on revolvable shafts as indicatedand over which passes conveyor 22 carrying at intervals a scraperbladeas shown at 23 so arranged that it will travel slowly along thebottom of the box inside of the same to carry along the chaff whichfalls from the coffee being roasted on thescreen and eject same to asmall opening in the bottom of the box into a discharge chute 24 at theextreme end of the apparatus.k Conveyor 22 may receive its powerV byareduction drive from shaft 13 as indicated at 25, or by any otherreduction drive from the motor 19 in the well understood manner, therequirements being simply that the conveyor moves very slowly tooccasionally carry out the accumulated chaif, as there is relativelyvery little of it as compared to the quantity of coffee passing over thescreen plate 7.

abelt or chain Arranged above the screen plate 7 and sub- .I

stantially continuously extending over its entire area both in widthandlength of the box` are "a multiplicity of electrical heating elements26 arranged in a flat layer. These elements extend longitudinally andare supported on transversely positioned, spaced insulating lbars 27 inlturn carried on insulating knobs 28 secured by concealed bolts 29 tothe upper Awall of the box.

Preferably also carried on the insulatorsv sheet of asbestos materialrial 30 backed by a metal sheet-31, the arrangement being such that theheat insulating and reiecting material 30 will both radiate and reflectany heat being emitted from the upperv side of the elements and force itdownwards towards the screen plate 7. It is also contemplated that theheating elements 26 themselves be each su plied with a radiating andreflecting metal tiii 26 such as the commercially obtainable electricair heating units made by the General Electric Company.

lThe electrical 4heating elements as described form a continuous web .orplane of radiant heat disposed arallel with and directly over the screenp ate 7, in practice separated therefrom about one to three inches, andduring operationl of themachine the elements are preferably maintainedat a heat just below a dull red, or at a range lying between 400 and 500degreesF., so as to effect a complete roastin of the beans in passingthereunder by a ra iant heat alone yet without any tendency to producesurface burns thereon before the roasting is complete.

The electrical heating .elements are connected up in any approvedfmannerand are energized b power wires enterin Athe box aseindicate at 32suitably contro led bya A switch not shown.

Vofco ee-beansthro or instance as heating the plates 30 or 26 means ofdownwardly directed gas jets from t above to make them radiate the heatas de-v of the screen weave and the violence andspeed of thev vibrationthereof. vWithan apparatusas described and with a speed oftravel rangingfrom 7 to 10 minutes along a screen from 20 to 30 o r more feet in le h,a constant ow of perfectly roasted co 4ee will fall from chute 5 to areceiving hopper such as that indicated at 34 for lassing the roastedbeans to an aerator or coo ing device pre aratoryl to grindin the same.

aving t us describe my invention it will be seen to suggestmodifications without departing from t e spirit of the invention, sugh Yscribed yet without permitting contact `of gas fumes with the coee layerpassing along the modifications coming screen and any such within thescope of the appended claims are intended to be covered I claim: v

1min- 1. Coiee roasting apparatus compri an elongated housing, a-shakertable 1n sai tate and carry a layer A ho arrangedtoa f .M th tabwsaidhou'sin,mea ns or e e an means or maui- Pg! :mzvgone of radiantheat above-and overlying the table. 2. Co ee roasting apparatuscomprising tially horizentalextension, a shaker-screen thereinsubstantially the length .with sai complete roastingV of the beans inone p r l ported in substantially horizontal extension,

a shaker screen therein arranged to receive a continuous suppl of coffeeat .one end fordischarge at the o er, means for operating the screen'for conveying the beans therethrough and tumbling them about, a layerof so r electrical heating elements arranged above the screen and inproximityv thereto,f'an'd heat radiatin and reflecting means associatedheatin elements adapted to radi-v ate and reflect tg coffee carried bythe screen.

4. In a structure as specified in claim 2, a 'luralty of bars extendingtransversely and freely through the housing and supporting said screen,and oscillable devices support-l 9 ing said bars outside of thehousing.. i

5. In a structure as s cied 1n claim 3, said housing being inclinedownwardly tcward' its discharge end and of a 'length to insure JOSEPHF. QUINN- 'y therethrough.

' an elongated housing supported in substan- A i e heat downwardsagainstV es

